93Nb(n,2n)92mNb, 93Nb(n,α)90mY and 92Mo(n,p)92mNb reactions at 14.78 MeV and covariance analysis

Journal of Radioanalytical and Nuclear Chemistry - The cross sections for the 93Nb(n,2n)92mNb, 93Nb(n,α)90mY and the 92Mo(n,p)92mNb reactions have been measured with respect to the...     

Laminar flow of power-law fluids past a rotating cylinder

In this work, the continuity and momentum equations have been solved numerically to investigate the flow of power-law fluids over a rotating cylinder. In particular, consideration has been given to the prediction of drag and lift coefficients as functions of the pertinent governing dimensionless parameters, namely, power-law index (1 ≥ n ≥ 0.2), dimensionless rotational velocity (0 ≤ α ≤ 6) and the Reynolds number (0.1 ≤ Re ≤ 40). Over the range of Reynolds number, the flow is known to be steady. Detailed streamline and vorticity contours adjacent to the rotating cylinder and surface pressure profiles provide further insights into the nature of flow. Finally, the paper is concluded by comparing the present numerical results with the scant experimental data on velocity profiles in the vicinity of a rotating cylinder available in the literature. The correspondence is seen to be excellent for Newtonian and inelastic fluids.     

Microsatellite instability and its correlation with clinicopathological features in a series of thyroid tumors prevalent in iodine deficient areas

Thyroid tumors display diverse spectrum of histopathological groups with geographic variation in its prevalence. Influence of iodine deficiency (a major causative factor) in its etiology, prevalence, or aggressiveness is debatable which reflects the existence of various genetic events in pathogenesis. The present study was undertaken to study the role of Microsatellite instability (MSI) or LOH (loss of heterozygosity), an indicator of defective mismatch repair system as a genetic change and to explore it as a prognostic marker in thyroid tumors. Tumor tissues from total thyroidectomy surgical specimens and blood (matched control) of 36 patients from iodine deficient areas (10 benign; 26 malignant) were obtained after their consent. Urinary iodine analysis was done by alkali ash method for which 10 ml of urine was collected from 18 patients before surgery. Genomic DNA, isolated from tumor tissue and blood was amplified by polymerase chain reaction (PCR) using mono and dinucleotide markers - BAT-26, BAT-40, TGF(RII, IGFIIR, hMSH3, BAX, D2S123, D9S283, D9S851 and D18S58. PCR products were analysed on 8% denaturing polyacrylamide gel followed by autoradiography. Of total, 66.6% of tumors [70% (7/10) benign and 65.4% malignant cases (17/26)] showed MSI/LOH. Strong association of MSI/LOH with low iodine (P = 0.01) and with AMES risk groups i.e. age (P = 0.02), tumor size (P = 0.04) and metastases (P = 0.002) in thyroid tumors was observed. This may help in predicting the biological behaviour and strengthening the hypothesis that iodine deficiency has influence on MSI in thyroid tumors. Our results further substantiate the risk group classification and help in deciding the treatment modality in particular patient.     

Tandem synthesis of [1,2,4]-triazoles mediated by iodine—a regioselective approach

A tandem regioselective one-pot synthesis of 3-amino-[1,2,4]-triazoles has been achieved from 1,3-disubstituted thioureas using molecular iodine. In this one-pot strategy, the intermediate carbodiimide generated in situ from thiourea upon reaction with HCONHNH₂ gives diaryl/alkylhydrazinecarboximidamide or acylureidrazone, which then undergoes an intramolecular cyclodehydration to afford the corresponding 3-amino-[1,2,4]-triazole. The product regioselectivity for unsymmetrical 1,3-disubstituted thioureas correlate well with the pK_as of the parent amines attached, in which the amine having higher pK_a goes to the ring nitrogen while the other nitrogen remains flanked as an exocyclic nitrogen of the triazole core. This method is milder and environmentally sustainable giving good to excellent yields of the desired products.     

Stereoselective synthesis of hydroxy stilbenoids and styrenes by atom-efficient olefination with thiophthalides

The synthesis of stilbenoids and styryl carboxylic acids is accomplished with high E-stereoselectivity by olefination of aldehydes with thiophthalides under basic conditions. The olefination is highly atom-efficient as it only loses elemental sulfur during the reaction. This olefination, in conjunction with retro Kolbe-Schmitt reaction, allows facile synthesis of E-hydroxystilbenoids with minimal employment of protecting groups. This study also discloses two important findings: formation of i) 4-methylsulfanyl isocoumarins and ii) an 2-arylindenone.     

Novel glucose derived non-ionic gemini surfactants as reverse micellar systems for encapsulation of d- and l-enantiomers of some aromatic α-amino acids in n-hexane

Novel glucose-based non-ionic gemini amphiphiles comprising two sugar head groups, two hydrophobic tails having chain length of C₁₂, C₁₄, and C₁₈ and a –CH₂–Ar–CH₂– spacer have been synthesized. The head groups of the geminis consist of glucose entities (with reducing function blocked in cyclic acetal group) connected through C-6 to tertiary amines. These amphiphiles were explored as reverse micellar systems, for the encapsulation of d- and l-enantiomers of ultraviolet-absorbing aromatic α-amino acids histidine (H), phenylalanine (F), tyrosine (Y) and tryptophan (W) in n-hexane, without any added water. Reverse micellar studies revealed that aromatic α-amino acids were encapsulated in the sequence H?>?F?>?Y?>?W. In most cases, specifically for F, d-enantiomer was found better encapsulated than l-enantiomer in the reverse micellar probes of the gemini surfactants.     

Prudent Practices in ex situ Durability Analysis Using Cyclic Voltammetry for Platinum-based Electrocatalysts

Platinum (Pt)-based electrocatalysts are at the vanguard of research initiatives to meet activity and durability targets for promoting large-scale adoption of fuel cell vehicles. Ex situ characterization of electrocatalyst activity and durability using cyclic voltammetry (CV) has a steep learning curve. Thus, many researchers who do not receive formal training in electrochemistry are left unsure how to proceed. Herein, we identify and compile prudent practices for reliable assessment of ECSA values with examples from our research on nanoscale catalytic films formed by the self-terminating electrodeposition of Pt. Starting with a conceptual framework to understand typical features in the CV of reversible redox couples, we present prudent practices in acquiring CV data aimed at nonelectrochemists. We then highlight specific features related to ECSA computation from Pt CV. Finally, we suggest safeguards that help avoid missteps and achieve repeatable results while conducting ex situ durability tests that extend over days.     

In Vitro and In Silico Studies for the Identification of Potent Metabolites of Some High-Altitude Medicinal Plants from Nepal Inhibiting SARS-CoV-2 Spike Protein

Despite ongoing vaccination programs against COVID-19 around the world, cases of infection are still rising with new variants. This infers that an effective antiviral drug against COVID-19 is crucial along with vaccinations to decrease cases. A potential target of such antivirals could be the membrane components of the causative pathogen, SARS-CoV-2, for instance spike (S) protein. In our research, we have deployed in vitro screening of crude extracts of seven ethnomedicinal plants against the spike receptor-binding domain (S1-RBD) of SARS-CoV-2 using an enzyme-linked immunosorbent assay (ELISA). Following encouraging in vitro results for Tinospora cordifolia, in silico studies were conducted for the 14 reported antiviral secondary metabolites isolated from T. cordifolia—a species widely cultivated and used as an antiviral drug in the Himalayan country of Nepal—using Genetic Optimization for Ligand Docking (GOLD), Molecular Operating Environment (MOE), and BIOVIA Discovery Studio. The molecular docking and binding energy study revealed that cordifolioside-A had a higher binding affinity and was the most effective in binding to the competitive site of the spike protein. Molecular dynamics (MD) simulation studies using GROMACS 5.4.1 further assayed the interaction between the potent compound and binding sites of the spike protein. It revealed that cordifolioside-A demonstrated better binding affinity and stability, and resulted in a conformational change in S1-RBD, hence hindering the activities of the protein. In addition, ADMET analysis of the secondary metabolites from T. cordifolia revealed promising pharmacokinetic properties. Our study thus recommends that certain secondary metabolites of T. cordifolia are possible medicinal candidates against SARS-CoV-2.     

Morphological,cytological and phytochemical studies in naturally occurring diploid and tetraploid populations of Physochlaina praealta from high altitudes of Trans-Himalaya

Physochlaina praealta samples were studied macromorphologically and cytomorphologically along with their detailed phytochemical investigation. The concentration of phytoconstituents showed a strong positive correlation with the ploidy level and altitudinal gradients. The total phenol content was detected maximum in the methanolic extract of leaves and stem of higher altitudinal plants in both cytotypes (2x, 4x). The maximum content of flavonoids was detected in the methanolic extract of root and leaves. Root organ from higher elevation possessed the highest DPPH radical scavenging activity, with the maximum percentage of inhibition being obtained in methanolic extracts. The plants of both cytotypes from higher elevations accumulate an abundant quantity of secondary metabolites. The two cytotypes differ from each other with respect to various morphometric characters thereby depicting the drastic affect of polyploidy.